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Bloodstream HSV-1 and HSV-2 infections can cause devastating outcomes with high morbidity and mortality, especially in neonates or immunocompromised individuals. Proper patient management for herpes simplex virus (HSV) bloodstream infections is time-sensitive and requires a rapid, accurate, and definitive diagnosis. The absence of the U.S. Food and Drug Administration (FDA)-approved molecular assays for HSV detection in blood, coupled with a lack of consensus on the optimal sample type, underscores the unmet need for improved diagnostics. We prospectively compared the cycle threshold values in paired samples including whole blood (WB), plasma, serum, and peripheral blood mononuclear cells (PBMCs) from patients with bloodstream HSV infections. This analysis employed a modified use of the FDA-cleared Simplexa HSV-1 & 2 Direct assay. The clinical performance in serum was assessed by comparing the results of 247 remnant specimens on this sample-to-answer platform to established laboratory-developed tests in a blinded fashion. Serum samples exhibited significantly lower cycle thresholds than whole blood samples [2.6 cycle threshold (Ct) bias, P < 0.001]. The modified Simplexa assay demonstrated 100% positive percent agreement for the detection of HSV-1 and HSV-2 DNA in serum samples and yielded an overall agreement of 95% (95% CI, 0.92 to 0.97), with a κ statistic of 0.75 (95% CI, 0.62 to 0.86) compared to the composite reference method. Discordance rates were 5.20% for HSV-1 and 0.81% for HSV-2. This investigation demonstrates that serum is an optimal specimen type for HSV detection when compared to several blood compartments. Serum offers a promising sample type for rapid and accurate diagnosis of HSV bloodstream infections using the modified Simplexa assay. IMPORTANCE: Rapid, accurate, and definitive diagnosis of herpes simplex virus (HSV) infections is crucial in clinical settings for patient management. The absence of FDA-authorized molecular assays for HSV-1/2 detection in blood, coupled with a lack of consensus on the optimal sample type, underscores the need for improved diagnostic methods. Furthermore, rapid diagnosis of HSV bloodstream infections enables timely administration of antiviral treatment, influences patient management decisions for those at high risk, and can contribute to shorter hospital stays, thereby reducing healthcare costs.
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This study evaluated the effectiveness of academic screening measures in relation to parent-reported diagnoses.Multicenter, retrospective cohort study including structured interviews, questionnaires, and chart reviews.Six North American cleft centers.Children (n = 391) with cleft lip and/or palate, ages 8 to 10 years of age (192 male) and their guardians were recruited during regular clinic visits.Parent and child ratings on the Pediatric Quality of Life Inventory (PedsQL) School Scale, child report on CleftQ School Scale, parent report on the Adaptive Behavior Assessment System-Third Edition Functional Academics (ABAS-FA) Scale and Child Behavior Checklist (CBCL) School Competency Scale, parent interview, and medical chart review.Risk for concerns ranged from 12% to 41%, with higher risk reflected on the CBCL-SC compared to other measures. Males with cleft palate were consistently at the highest risk. Only 9% of the sample had a parent-reported diagnosis of a learning or language disability. Ratings from the ABAS-FA and CBCL-SC had the highest utility in identifying those with language and/or learning concerns.As cleft teams work to develop standardized batteries for screening and monitoring of patients, it is important to evaluate the effectiveness of measures in identifying those at highest risk. When screening for language and learning disorders, questions related to potential academic struggles, such as increased school effort or increased school distress, are most useful. Referrals for follow-up evaluation are recommended for those identified at high risk.
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Labio Leporino , Fisura del Paladar , Niño , Humanos , Masculino , Calidad de Vida , Estudios Retrospectivos , Estudiantes , FemeninoRESUMEN
BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is characterized by progressive loss of cardiomyocytes with fibrofatty tissue replacement, systolic dysfunction, and life-threatening arrhythmias. A substantial proportion of ACM is caused by mutations in genes of the desmosomal cell-cell adhesion complex, but the underlying mechanisms are not well understood. In the current study, we investigated the relevance of defective desmosomal adhesion for ACM development and progression. METHODS: We mutated the binding site of DSG2 (desmoglein-2), a crucial desmosomal adhesion molecule in cardiomyocytes. This DSG2-W2A mutation abrogates the tryptophan swap, a central interaction mechanism of DSG2 on the basis of structural data. Impaired adhesive function of DSG2-W2A was confirmed by cell-cell dissociation assays and force spectroscopy measurements by atomic force microscopy. The DSG2-W2A knock-in mouse model was analyzed by echocardiography, ECG, and histologic and biomolecular techniques including RNA sequencing and transmission electron and superresolution microscopy. The results were compared with ACM patient samples, and their relevance was confirmed in vivo and in cardiac slice cultures by inhibitor studies applying the small molecule EMD527040 or an inhibitory integrin-αVß6 antibody. RESULTS: The DSG2-W2A mutation impaired binding on molecular level and compromised intercellular adhesive function. Mice bearing this mutation develop a severe cardiac phenotype recalling the characteristics of ACM, including cardiac fibrosis, impaired systolic function, and arrhythmia. A comparison of the transcriptome of mutant mice with ACM patient data suggested deregulated integrin-αVß6 and subsequent transforming growth factor-ß signaling as driver of cardiac fibrosis. Blocking integrin-αVß6 led to reduced expression of profibrotic markers and reduced fibrosis formation in mutant animals in vivo. CONCLUSIONS: We show that disruption of desmosomal adhesion is sufficient to induce a phenotype that fulfils the clinical criteria to establish the diagnosis of ACM, confirming the dysfunctional adhesion hypothesis. Deregulation of integrin-αVß6 and transforming growth factor-ß signaling was identified as a central step toward fibrosis. A pilot in vivo drug test revealed this pathway as a promising target to ameliorate fibrosis. This highlights the value of this model to discern mechanisms of cardiac fibrosis and to identify and test novel treatment options for ACM.
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Displasia Ventricular Derecha Arritmogénica , Cardiomiopatías , Ratones , Animales , Cardiomiopatías/genética , Arritmias Cardíacas/genética , Arritmias Cardíacas/metabolismo , Integrinas/metabolismo , Miocitos Cardíacos/metabolismo , Fibrosis , Factor de Crecimiento Transformador beta/metabolismo , Factores de Crecimiento Transformadores/metabolismo , Displasia Ventricular Derecha Arritmogénica/patologíaRESUMEN
This observational, multisite cohort study explored health-related quality of life (HRQoL) in children with cleft lip and/or palate (CL/P), including interrater agreement and ratings for this group relative to clinical cutoff scores and published means for healthy and chronically ill children.Participants (338 children ages 8-10 years, 45.9% male and their parents, 82.0% female) across 6 sites completed the Pediatric Quality of Life Inventory Generic Core Scales (PedsQL).Intraclass correlation revealed poor interrater agreement for most HRQoL domains. Although ratings were generally higher than those expected for children with a chronic illness, child ratings were below healthy means for school functioning, and parent proxy ratings were below healthy means for all domains except physical functioning. Lower ratings consistent with chronic illness means were found for self-reported emotional and psychosocial functioning in children with cleft lip and palate (CLP), as well as parent proxy-reported emotional, school, and psychosocial functioning for children with cleft palate (CP). Scores were most likely to be in the clinical range for children with CP for social, school, and total functioning.Although parent proxy report provides important information about observed functioning, poor interrater agreement indicates that both child and parent proxy reported HRQoL should be included in outcomes assessment for CL/P. HRQoL ratings may be higher for children with CL/P compared to youth with other chronic illnesses, but psychosocial functioning may be negatively impacted when compared with healthy youth, particularly for emotional, social, and school functioning in children with CLP or CP.
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Labio Leporino , Fisura del Paladar , Adolescente , Niño , Humanos , Masculino , Femenino , Calidad de Vida/psicología , Labio Leporino/psicología , Fisura del Paladar/psicología , Estudios de Cohortes , Padres/psicología , Enfermedad CrónicaRESUMEN
OBJECTIVE: To determine associations of demographic, morphologic, and treatment protocol parameters with quality of life (QoL), appearance/speech satisfaction, and psychological adjustment. DESIGN: Observational study utilizing retrospective report of protocol variables and current outcome variables. SETTING: Six North American cleft treatment clinics. PARTICIPANTS: Children, ages 8.0-10.99 years, with Cleft Lip ± Alveolus, Cleft Palate, Cleft Lip and Palate, and parents (N = 284). OUTCOME MEASURES: Pediatric QoL Inventory (PedsQL): Parent, Child, Family Impact Module (FIM); Patient Reported Outcome Measurement Information System (PROMIS); Child Behavior Checklist (CBCL); CLEFT-Q. RESULTS: Outcome scores were average with few differences by cleft type. Multiple regression analyses yielded significant associations (Ps < .05) between socioeconomic status, race, and age at assessment and parent- and self-reported measures. Females had higher PROMIS Depression (ß=.20) but lower CBCL Affective (ß = -.16) and PROMIS Stigma scores (ß= -.24). Incomplete cleft lip was associated with lower PROMIS Depression, and more positive ratings of CLEFT-Q: Nose, Nostril, Lip Scar; CBCL Competence scores, (ßs = -.17 to .17). Younger Age at Lip Closure was associated with higher CBCL School Competence (ß= -.18). Younger Age at Palate Closure was associated with higher Child PedsQL Total, Physical, Psychosocial QoL, and better CLEFT-Q Speech Function (ßs = -.18 to -.15). Furlow Palatoplasty was associated with more CBCL Externalizing Problems (ß = .17) higher CBCL Activities (ß = .16). For all diagnoses, fewer Total Cleft-Related Surgeries was associated with lower PROMIS Stigma and higher CBCL Total Competence and Activities (ßs = -.16 to .15). CONCLUSIONS: Demographic characteristics, lip morphology, and treatment variables are related to later psychological functioning.
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OBJECTIVE: The purpose of this study was to evaluate possible relationships between number of surgeries and parent ratings of academic functioning among children with isolated oral clefts. DESIGN: Multicenter, retrospective cohort study including structured interviews, questionnaires, and chart reviews. SETTING: Completion of questionnaires occurred during clinical visits at 6 different cleft centers across North America. PARTICIPANTS: Parents of 285 children with isolated clefts of the lip and/or palate, aged 8 to 10 years old, participated in structured interviews and completed questionnaires regarding the academic and behavioral functioning of their children. MAIN OUTCOME MEASURES: Parent interview and medical chart review of number of surgeries to date and parent ratings on the Adaptive Behavior Assessment System, Third Edition-Functional Academics Scale (ABAS-FA) and Child Behavior Checklist (CBCL) Total Competency Scale. RESULTS: Parent ratings of ABAS-FA were at or above normative expectations, while ratings across CBCL Competency Scales were lower than normative expectations. Socioeconomic status (SES), age, and race were consistent predictors of parent ratings (higher SES, older age, and Caucasian race were associated with better functioning). Number of surgeries did not add significantly to academic ratings but did significantly contribute to ratings of social and activity participation. Patients with more surgeries were rated with lower functioning in these domains. CONCLUSIONS: Findings do not support a connection between number of surgeries and later ratings of academic functioning but do support a connection to social and activity involvement. Recommendations for conducting direct studies of the connection between surgeries and academic functioning as well as clinical considerations for surgeries and impact on social and activity involvement are discussed.
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Fisura del Paladar , Anciano , Niño , Fisura del Paladar/cirugía , Humanos , Padres , Estudios Retrospectivos , Clase Social , Encuestas y CuestionariosRESUMEN
The functional maturation and preservation of hepatic cells derived from human induced pluripotent stem cells (hiPSCs) are essential to personalized in vitro drug screening and disease study. Major liver functions are tightly linked to the 3D assembly of hepatocytes, with the supporting cell types from both endodermal and mesodermal origins in a hexagonal lobule unit. Although there are many reports on functional 2D cell differentiation, few studies have demonstrated the in vitro maturation of hiPSC-derived hepatic progenitor cells (hiPSC-HPCs) in a 3D environment that depicts the physiologically relevant cell combination and microarchitecture. The application of rapid, digital 3D bioprinting to tissue engineering has allowed 3D patterning of multiple cell types in a predefined biomimetic manner. Here we present a 3D hydrogel-based triculture model that embeds hiPSC-HPCs with human umbilical vein endothelial cells and adipose-derived stem cells in a microscale hexagonal architecture. In comparison with 2D monolayer culture and a 3D HPC-only model, our 3D triculture model shows both phenotypic and functional enhancements in the hiPSC-HPCs over weeks of in vitro culture. Specifically, we find improved morphological organization, higher liver-specific gene expression levels, increased metabolic product secretion, and enhanced cytochrome P450 induction. The application of bioprinting technology in tissue engineering enables the development of a 3D biomimetic liver model that recapitulates the native liver module architecture and could be used for various applications such as early drug screening and disease modeling.
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Bioimpresión/métodos , Hepatocitos/citología , Células Madre Pluripotentes Inducidas/citología , Hígado/anatomía & histología , Impresión Tridimensional , Albúminas/biosíntesis , Biomimética/métodos , Técnicas de Cultivo de Célula , Diferenciación Celular , Expresión Génica , Hepatocitos/metabolismo , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Hígado/citología , Ingeniería de Tejidos/métodosAsunto(s)
Calcio , Insuficiencia Cardíaca , Humanos , Volumen Sistólico , Insuficiencia Cardíaca/patología , FenotipoRESUMEN
Cardiac muscle cells have an intrinsic ability to sense and respond to mechanical load through a process known as mechanotransduction. In the heart, this process involves the conversion of mechanical stimuli into biochemical events that induce changes in myocardial structure and function. Mechanotransduction and its downstream effects function initially as adaptive responses that serve as compensatory mechanisms during adaptation to the initial load. However, under prolonged and abnormal loading conditions, the remodeling processes can become maladaptive, leading to altered physiological function and the development of pathological cardiac hypertrophy and heart failure. Although the mechanisms underlying mechanotransduction are far from being fully elucidated, human and mouse genetic studies have highlighted various cytoskeletal and sarcolemmal structures in cardiac myocytes as the likely candidates for load transducers, based on their link to signaling molecules and architectural components important in disease pathogenesis. In this review, we summarize recent developments that have uncovered specific protein complexes linked to mechanotransduction and mechanotransmission within the sarcomere, the intercalated disc, and at the sarcolemma. The protein structures acting as mechanotransducers are the first step in the process that drives physiological and pathological cardiac hypertrophy and remodeling, as well as the transition to heart failure, and may provide better insights into mechanisms driving mechanotransduction-based diseases.
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Cardiomegalia/metabolismo , Insuficiencia Cardíaca/metabolismo , Hemodinámica , Mecanotransducción Celular , Proteínas Musculares/metabolismo , Miocitos Cardíacos/metabolismo , Adaptación Fisiológica , Animales , Cardiomegalia/genética , Cardiomegalia/patología , Cardiomegalia/fisiopatología , Insuficiencia Cardíaca/genética , Insuficiencia Cardíaca/patología , Insuficiencia Cardíaca/fisiopatología , Humanos , Complejos Multiproteicos , Proteínas Musculares/genética , Miocitos Cardíacos/patologíaRESUMEN
Development of cardiac fibrosis and arrhythmias is controlled by the activity of and communication between cardiomyocytes and fibroblasts in the heart. Myocyte-fibroblast interactions occur via both direct and indirect means including paracrine mediators, extracellular matrix interactions, electrical modulators, mechanical junctions, and membrane nanotubes. In the diseased heart, cardiomyocyte and fibroblast ratios and activity, and thus myocyte-fibroblast interactions, change and are thought to contribute to the course of disease including development of fibrosis and arrhythmogenic activity. Fibroblasts have a developing role in modulating cardiomyocyte electrical and hypertrophic activity, however gaps in knowledge regarding these interactions still exist. Research in this field has necessitated the development of unique approaches to isolate and control myocyte-fibroblast interactions. Numerous methods for 2D and 3D co-culture systems have been developed, while a growing part of this field is in the use of better tools for in vivo systems including cardiomyocyte and fibroblast specific Cre mouse lines for cell type specific genetic ablation. This review will focus on (i) mechanisms of myocyte-fibroblast communication and their effects on disease features such as cardiac fibrosis and arrhythmias as well as (ii) methods being used and currently developed in this field.
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Arritmias Cardíacas/metabolismo , Comunicación Celular , Fibroblastos/metabolismo , Miocardio/metabolismo , Miocitos Cardíacos/metabolismo , Animales , Arritmias Cardíacas/fisiopatología , Técnicas de Cocultivo , Modelos Animales de Enfermedad , Matriz Extracelular/metabolismo , Proteínas de la Matriz Extracelular/metabolismo , Fibrosis , Humanos , Técnicas In Vitro , Modelos Biológicos , Miocardio/patologíaRESUMEN
Arrhythmogenic right ventricular cardiomyopathy (ARVC) termed a 'disease of the desmosome' is an inherited cardiomyopathy that recently underwent reclassification owing to the identification of left-dominant and biventricular disease forms. Homozygous loss-of-function mutations in the desmosomal component, desmoplakin, are found in patients exhibiting a biventricular form of ARVC; however, no models recapitulate the postnatal hallmarks of the disease as seen in these patients. To gain insights into the homozygous loss-of-function effects of desmoplakin in the heart, we generated cardiomyocyte-specific desmoplakin-deficient mice (DSP-cKO) using ventricular myosin light chain-2-Cre mice. Homozygous DSP-cKO mice are viable but display early ultrastructural defects in desmosomal integrity leading to a cardiomyopathy reminiscent of a biventricular form of ARVC, which includes cell death and fibro-fatty replacement within the ventricle leading to biventricular dysfunction, failure and premature death. DSP-cKO mice also exhibited ventricular arrhythmias that are exacerbated with exercise and catecholamine stimulation. Furthermore, DSP-cKO hearts exhibited right ventricular conduction defects associated with loss of connexin 40 expression and electrical wavefront propagation defects associated with loss of connexin 43 expression. Dose-dependent assessment of the effects of loss of desmoplakin in neonatal ventricular cardiomyocytes revealed primary loss of connexin 43 levels, phosphorylation and function independent of the molecular dissociation of the mechanical junction complex and fibro-fatty manifestation associated with ARVC, suggesting a role for desmoplakin as a primary stabilizer of connexin integrity. In summary, we provide evidence for a novel mouse model, which is reminiscent of the postnatal onset of ARVC while highlighting mechanisms underlying a biventricular form of human ARVC.
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Displasia Ventricular Derecha Arritmogénica/genética , Conexinas/deficiencia , Animales , Animales Recién Nacidos , Arritmias Cardíacas/genética , Displasia Ventricular Derecha Arritmogénica/diagnóstico , Displasia Ventricular Derecha Arritmogénica/mortalidad , Síndrome de Brugada , Trastorno del Sistema de Conducción Cardíaco , Catecolaminas/farmacología , Conexina 43/deficiencia , Conexina 43/genética , Conexina 43/metabolismo , Conexinas/genética , Desmoplaquinas/deficiencia , Modelos Animales de Enfermedad , Electrocardiografía , Expresión Génica , Corazón/efectos de los fármacos , Sistema de Conducción Cardíaco/anomalías , Imagen por Resonancia Magnética , Ratones , Ratones Noqueados , Miocardio/metabolismo , Miocardio/patología , Miocardio/ultraestructura , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Miocitos Cardíacos/ultraestructura , Fosforilación , Condicionamiento Físico Animal/efectos adversos , Proteína alfa-5 de Unión ComunicanteRESUMEN
Recent human genetic studies have provided evidences that sporadic or inherited missense mutations in four-and-a-half LIM domain protein 1 (FHL1), resulting in alterations in FHL1 protein expression, are associated with rare congenital myopathies, including reducing body myopathy and Emery-Dreifuss muscular dystrophy. However, it remains to be clarified whether mutations in FHL1 cause skeletal muscle remodeling owing to gain- or loss of FHL1 function. In this study, we used FHL1-null mice lacking global FHL1 expression to evaluate loss-of-function effects on skeletal muscle homeostasis. Histological and functional analyses of soleus, tibialis anterior and sternohyoideus muscles demonstrated that FHL1-null mice develop an age-dependent myopathy associated with myofibrillar and intermyofibrillar (mitochondrial and sarcoplasmic reticulum) disorganization, impaired muscle oxidative capacity and increased autophagic activity. A longitudinal study established decreased survival rates in FHL1-null mice, associated with age-dependent impairment of muscle contractile function and a significantly lower exercise capacity. Analysis of primary myoblasts isolated from FHL1-null muscles demonstrated early muscle fiber differentiation and maturation defects, which could be rescued by re-expression of the FHL1A isoform, highlighting that FHL1A is necessary for proper muscle fiber differentiation and maturation in vitro. Overall, our data show that loss of FHL1 function leads to myopathy in vivo and suggest that loss of function of FHL1 may be one of the mechanisms underlying muscle dystrophy in patients with FHL1 mutations.
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Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas con Dominio LIM/genética , Proteínas con Dominio LIM/metabolismo , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Músculo Esquelético/patología , Distrofias Musculares/patología , Miofibrillas/patología , Factores de Edad , Animales , Diferenciación Celular , Femenino , Humanos , Masculino , Ratones , Ratones Transgénicos , Actividad Motora , Músculo Esquelético/metabolismo , Distrofias Musculares/genética , Distrofia Muscular de Emery-Dreifuss/patología , Mioblastos Esqueléticos/metabolismo , Mioblastos Esqueléticos/patología , Miofibrillas/metabolismoRESUMEN
PKA signaling is important for the post-translational modification of proteins, especially those in cardiomyocytes involved in cardiac excitation-contraction coupling. PKA activity is spatially and temporally regulated through compartmentalization by protein kinase A anchoring proteins. Cypher/ZASP, a member of PDZ-LIM domain protein family, is a cytoskeletal protein that forms multiprotein complexes at sarcomeric Z-lines. It has been demonstrated that Cypher/ZASP plays a pivotal structural role in the structural integrity of sarcomeres, and several of its mutations are associated with myopathies including dilated cardiomyopathy. Here we show that Cypher/ZASP, interacting specifically with the type II regulatory subunit RIIα of PKA, acted as a typical protein kinase A anchoring protein in cardiomyocytes. In addition, we show that Cypher/ZASP itself was phosphorylated at Ser(265) and Ser(296) by PKA. Furthermore, the PDZ domain of Cypher/ZASP interacted with the L-type calcium channel through its C-terminal PDZ binding motif. Expression of Cypher/ZASP facilitated PKA-mediated phosphorylation of the L-type calcium channel in vitro. Additionally, the phosphorylation of the L-type calcium channel at Ser(1928) induced by isoproterenol was impaired in neonatal Cypher/ZASP-null cardiomyocytes. Moreover, Cypher/ZASP interacted with the Ser/Thr phosphatase calcineurin, which is a phosphatase for the L-type calcium channel. Taken together, our data strongly suggest that Cypher/ZASP not only plays a structural role for the sarcomeric integrity, but is also an important sarcomeric signaling scaffold in regulating the phosphorylation of channels or contractile proteins.
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Proteínas Adaptadoras Transductoras de Señales/metabolismo , Canales de Calcio Tipo L/metabolismo , Subunidad RIIalfa de la Proteína Quinasa Dependiente de AMP Cíclico/metabolismo , Proteínas con Dominio LIM/metabolismo , Proteínas Adaptadoras Transductoras de Señales/química , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Animales Recién Nacidos , Células Cultivadas , Subunidad RIIalfa de la Proteína Quinasa Dependiente de AMP Cíclico/química , Subunidad RIIalfa de la Proteína Quinasa Dependiente de AMP Cíclico/genética , Células HEK293 , Humanos , Immunoblotting , Proteínas con Dominio LIM/química , Proteínas con Dominio LIM/genética , Ratones , Ratones Noqueados , Modelos Moleculares , Mutación , Miocardio/metabolismo , Miocitos Cardíacos/citología , Miocitos Cardíacos/metabolismo , Dominios PDZ/genética , Fosforilación , Unión Proteica , Ratas , Sarcómeros/metabolismo , Serina/química , Serina/genética , Serina/metabolismoRESUMEN
Understanding mechanisms underlying titin regulation in cardiac muscle function is of critical importance given recent compelling evidence that highlight titin mutations as major determinants of human cardiomyopathy. We previously identified a cardiac biomechanical stress-regulated complex at the cardiac-specific N2B region of titin that includes four-and-a-half LIM domain protein-1 (Fhl1) and components of the mitogen-activated protein signaling cascade, which impacted muscle compliance in Fhl1 knock-out cardiac muscle. However, direct regulation of these molecular components in mediating titin N2B function remained unresolved. Here we identify Fhl1 as a novel negative regulator of titin N2B levels and phosphorylation-mediated mechanics. We specifically identify titin N2B as a novel substrate of extracellular signal regulated-kinase-2 (Erk2) and demonstrate that Fhl1 directly interferes with Erk2-mediated titin-N2B phosphorylation. We highlight the critical region in titin-N2B that interacts with Fhl1 and residues that are dependent on Erk2-mediated phosphorylation in situ. We also propose a potential mechanism for a known titin-N2B cardiomyopathy-causing mutation that involves this regulatory complex. These studies shed light on a novel mechanism regulating titin-N2B mechano-signaling as well as suggest that dysfunction of these pathways could be important in cardiac disease states affecting muscle compliance.
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Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas con Dominio LIM/metabolismo , Mecanotransducción Celular , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteínas Musculares/metabolismo , Miocardio/metabolismo , Proteínas Quinasas/metabolismo , Animales , Cardiomiopatías/metabolismo , Cardiomiopatías/patología , Conectina , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Proteínas con Dominio LIM/genética , Ratones , Ratones Noqueados , Proteína Quinasa 1 Activada por Mitógenos/genética , Proteínas Musculares/genética , Mutación , Miocardio/patología , Fosforilación , Proteínas Quinasas/genética , Estructura Terciaria de ProteínaRESUMEN
Cypher long (CypherL) and short (CypherS) isoforms are distinguished from each other by the presence and absence of three C-terminal LIM domains, respectively. Cypher isoforms are developmentally regulated, and mutations affecting both long and short isoforms are linked to muscle disease in humans. Given these data, we hypothesized that various Cypher isoforms play overlapping and unique roles in striated muscle. To determine the specific role of Cypher isoforms in striated muscle, we generated two mouse lines in which either CypherS or CypherL isoforms were specifically deleted. Mice specifically, deficient in CypherS isoforms had no detectable muscle phenotype. In contrast, selective loss of CypherL isoforms resulted in partial neonatal lethality. Surviving mutants exhibited growth retardation and late-onset dilated cardiomyopathy, which was associated with cardiac fibrosis and calcification, leading to premature adult mortality. At a young age, preceding development of cardiomyopathy, hearts from these mutants exhibited defects in both Z-line ultrastructure and specific aberrations in calcineurin-NFAT and protein kinase C pathways. Earlier onset of cardiac dilation relative to control wild-type mice was observed in young CypherL isoform knockout mice consequent to pressure overload, suggesting a greater susceptibility to the disease. In summary, we have identified unique roles for CypherL isoforms in maintaining Z-line ultrastructure and signaling that are distinct from the roles of CypherS isoforms, while highlighting the contribution of mutations in the long isoforms to the development of dilated cardiomyopathy.
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Cardiomiopatía Dilatada/genética , Proteínas Portadoras/genética , Eliminación de Gen , Proteínas de Homeodominio/genética , Proteínas Adaptadoras Transductoras de Señales , Animales , Cardiomiopatía Dilatada/metabolismo , Cardiomiopatía Dilatada/patología , Proteínas Portadoras/metabolismo , Modelos Animales de Enfermedad , Femenino , Proteínas de Homeodominio/metabolismo , Humanos , Proteínas con Dominio LIM , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Músculo Estriado/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismoRESUMEN
Myoblasts are precursor muscle cells that lie nascent to mature skeletal muscle. Once muscle is damaged, these cells migrate, fuse, and regenerate the muscle tissue. It is known that skeletal muscle can partially regenerate in vivo after muscle tissue damage. However, this regeneration does not always occur, especially in more severe injuries. Cellular therapy using tissue-engineering approaches has been shown to improve organ repair and function. To exploit potential benefits of using cell therapy as an avenue for skeletal muscle repair, it is important to understand the cellular dynamics underlying skeletal myocyte formation and growth. Cardiac fibroblasts have been shown to have a major influence on cardiomyocyte function, repair, and overall spatial distribution. However, little is known regarding fibroblasts' role on skeletal myocyte function. In this study, we utilized a reconfigurable co-culture device to understand the contact and paracrine effects of fibroblasts on skeletal myocyte alignment and differentiation using murine myoblast and fibroblast cell lines. We demonstrate that myotube alignment is increased by direct contact with fibroblasts, while myotube differentiation is reduced both in the gap and contact configurations with fibroblasts after 6 days of co-culture. Furthermore, neutralizing antibodies to FGF-2 can block these effects of fibroblasts on myotube differentiation and alignment. Finally, bi-directional signaling is critical to the observed myoblast-fibroblast interactions, since conditioned media could not reproduce the same effects observed in the gap configuration. These findings could have direct implications on cell therapies for repairing skeletal muscle, which have only utilized skeletal myoblasts or stem cell populations alone.
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Diferenciación Celular , Técnicas de Cocultivo/instrumentación , Fibroblastos/citología , Músculo Esquelético/citología , Mioblastos/citología , Células 3T3 , Animales , Comunicación Celular , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Fibroblastos/metabolismo , Ratones , Células Musculares/citología , Mioblastos/metabolismoRESUMEN
Myocarditis is frequently associated with viral infections. Increasing evidence points to an association between myocarditis and inherited cardiomyopathies, though it is unclear whether myocarditis is a driver or an accessory. We present a primary vignette and case series highlighting recurrent myocarditis in patients later found to harbor pathogenic desmosomal variants and provide clinical and basic science context, exploring 2 potentially overlapping hypotheses: that stress induces cellular injury and death in structurally abnormal myocytes and that recurrent viral myocardial and truncated desomosomal protein byproducts as 2 hits could lead to loss of immune tolerance and subsequent autoreactivity.
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Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a fatal genetic heart disease characterized by cardiac arrhythmias, in which fibrofatty deposition leads to heart failure, with no effective treatments. Plakophilin 2 (PKP2) is the most frequently mutated gene in ARVC, and although altered RNA splicing has been implicated, there are no models to study its effect and therapeutics. Here, we generate a mouse model harboring a PKP2 mutation (IVS10-1G>C) affecting RNA splicing, recapitulating ARVC features and sudden death starting at 4 weeks. Administering AAV-PKP2 gene therapy (adeno-associated viral therapy to drive cardiac expression of PKP2) to neonatal mice restored PKP2 protein levels, completely preventing cardiac desmosomal and pathological deficits associated with ARVC, ensuring 100% survival of mice up to 6 months. Late-stage AAV-PKP2 administration rescued desmosomal protein deficits and reduced pathological deficits including improved cardiac function in adult mice, resulting in 100% survival up to 4 months. We suggest that AAV-PKP2 gene therapy holds promise for circumventing ARVC associated with PKP2 mutations, including splice site mutations.